Polyester from terephthalic acid, ethylene glycol and polyethylene glycol



i United States Patent P'ontd Nemours andQCiJmpany;- ,Wilmington, DleL',corporation of Delaware N0.Drawing.= Applicationt'DecemberslU.1951,..

SeriaLNm 261 1501! 5 "Claimsa (CI. 2604-75) This invention. relates. to.a; modified. polyethylene tereph'thalate .having. ,improved dyeingproperties.

The production. of; the. noyeLv class of. fiberrformingg linear.polyesters. of terephthalic acid and a glycoltoft the seniesr.HO,'(CHz).tOH .Where -n.is' taninteger fromn2ato 4.0;: inclusiye.is,.-fullydisclosed in U.. S. Patent-1 2,465,319r Fromta. commercial;standpoint. one. ofthemosh-interaestingmplymers .of this classis.polyeth'ylene.terephthalater; However, ,for .all. of.its =desirable.characteristics,.. this.pply; mer. .does. suifer. by possessingarelatively ppon-aflinityfor; the, most; commonly, used .dyes under.thewconditioris-snormally employed. .fon. dyeing One.-. approach to.this .prohlenriv has; been-.- to.. prepare-r. copolymers of polyethyleneterephthalate with; other;polymerfforming,materials:whichapossessa:highqaflinity for:therdye1stnffs..commonlyeusedninz the:trade;. Ofithe; hundredslofncopplymers: prepared... only, one classls hash shown improveddyeing.:properties.without simultaneously; showing .a:severemetrogression.inz-the.physicalrproperties Q suchuasl resiliency,tenacity; andr 'softem'n z; emperature.

It. is aniobjectof this inyentiomtoprovide: ac copolyesten: ofpolyethylene. terephthalate.Which..-will show improvedr: dyeingproperties... It.-is..a further. object oftthiszinyentiom to. :proyide areadily,dyeablecop9lyesteri whichswill have-z physical properties;equivalents or nearly equiyalenta to; those.possessed-thy the.unmodified.spplyethylenet-.terephe 40 thalates. Other; objects will..becomelapparentteiin. the;-.-de+ scriptiomof; the.lfiV6I1fi'OI].'-..aI1d1inE the. claims; A

The..objects of :this ,.inventionsaretaccomp lished .zby suhs jecting.dimethyl,terephthalate;. ethylene glycoLand amply-p ethylene glycol asdefined below to .-aniesten.interchang e,- 5 reactionfollowedsby.polyrnerizationato.produce,a.copolyester. Thespplyethyleneglycollmay; be-rany oiifthecom-.-- pounds described by the formulae.

where'zn issantinmgersvarying fromsl M 13 5; on even mores- Thepolyethylene glycol may have a single molecularweight it may ,be.a blend0.a low..and a high molecular weight-compound, or'it 'may be ablndofseveralcompoundsrofagraduating;moleculanweighta. ltsispreterredhowever,Jhat.thepolyethylene-sglycol beanpure polymer:or..alrnixtureofrsuchpolymers.having;;a relatively narrowrangeofmoleculanweightss; The.amount;ofipplyethylene z glycol based on theweight of the dimethyl-sterephthal-atea may ,range .up .to.,ab0ut-.1 0%..without :tQOlSflIiQUSlX alfecting gthe. physicali prop ertiesr of theresulting; coprolymers but to get the best'balance of physical'propertieswandi dyeing properties, it is preferred to employpolyethylene glycolszinz amounts ranging-:ffom--about 1 to --about 5 Theester interchange reaction. and, the polymerization. reaction are1carried"'out essentially as described .Iin U.1.' S.,..P'atent2,534,0285. The. ethyleneglycoland the di'metliyl tereplithalatereact to form bis=flFhydioxyetliyl fterephthal; ate and in the presenceof the polyethylene. glycol Zsomeof the methanol residues of thedimetliylf'terephthalate are replaced withipolythylenerglycol-lrcsidesa. Ittmaythusubeob'servedtlfat the resulting prodtict'is amixture contain .ing, bisz-fl-hydroxyethyl terephthalate the:symmetrical ester 1 formed from two mols "of the 1 polyethylene glycoland-1 mol of 'dimethylterephthalate an'dth'e "unsymmetricalester-(formed fromzone mol of ethylene.glycol, onemol oflpolyetliylene:glycoh and one molt of dimethyl'f terephthala-te. This ester:interchangeereaction is broughtabout inlthe presenceiof; a;catalyst,=,e. g;,,,.lithargeein,a. concentration ranging from 005% up; to 1% -byheating the ingredients in a vessel adaptedifor distillationiatatemperature between C. and 220'? C..and=i'preferablyv between Cliand20,06 The reactionz-maybe car?" ried. out. under. pressures...above...or, below. atmospheric. pressure if desired. However, it canbereadily-seemthat an economic advantageresidest'initconductinggtlierreaca tion at atmospheric.-.press11re:The-ivolatileuproduct'.of the reaction, methanol, istakemoffi.overheadgandififorces the ester interchange reaction to completion.

The: subsequent polymerization reaction may be effected 'in eitherthe-=liquid "(i.- 6.; the melt) or-soli'd phase."-

ln the liquid phase the -reactionais=carried-' out" at reduced pressurein the vicinity of .05 to 20 millimeters of mercury with the range -.05to-5f0tmi1liineters *o-f mercury preferred for optimum results. At thisreduced pressure the freesethylene glycol zwhichemerges-Efrem thepolymer-as azresultzof: the condensation -reaction is removedz Thereactio mixture isigvery viscous. If the free ethyle'neglycol;:isxnotasubstantially removed; itis not possibl to form-tafiber-storming:polymericr:material, but rathera lowvnrolcular"weight-polymer.- too: brittle foe fibers -results. A temperaturebetween about *230 "C. to 290? G1 andnpreferablyrbetween .abouta260 0;to -about- 275" C.

is gmaintained iduring.zthe polymerization step; Since lowlength of timerequired varies, of course; with catalyst? concentration, temperature, Iintrinsic viscosity desired, amountof-colorallowable in-thefinishedpolymer, degree of.-j.vaeuumxobtaineda and many other such items. In

general-g itis desiredtnotttozhaveatooalongtia polymerization cycl,;.,bth fomeconomic reasonsandfor'thereason that if the polymerizationicycleis too long, the competing and irreversible thermafdgradation reactionwillh'ave sufficint time to lower theintrinsic-viscositymore'thantheepolymerization ireaction, can. raise-itt. w 'The followingexamplesil'lustrateth'e' preparation oft" thercopolyesters ofthisinventiom- Parts-and percentages? arerby Weight unless otherwiseindicated.

The... copolyesters were. prepared...by. the general pro cedureeofi"taking; 191 (h gramseofz; dimethyl terephthalate; 20. 105.- grams:ethylene: glycol, 0;23 gram. of-& lead? oxideand the weight of the givenpolyethylene"glycol shown im-Tablelii- Theerespective ingredients for?eacha copolymen: wereeput intoaa l roun'cl'f bottorned =-Claisen Idistilling iiask':madessof 'glass which was-heated to 190" G. fowl to 5liours' until the theoretical quantity-'of'meth'anol had" b'eemdistilld0ft." Th'e resulti'rigyprodiict was then transferred toa stainless-steelautoclave. Thistautoclave was evacuated. to 'a pressure 013.105 tol millimeter. mercury.

and 1118 temperature raised to 260"" C, the entiremixture.

being agltatediby bubbling-roxygenrfree nitrogenthroughcienmlngth;of...time..to..giye.a polymer v having intrinsi'ce viscosityin the range of 0.48 to 0.62. in Table I, there are also shown theimportant physical properties of the resulting copolymers.

Table 1 Avg. M. W. Percent Grains S. P. Percent Item of PE 1 PEG PE 0 s0. 12.

150 2. 5 47. 7 0. 58 247 2. 8 61 150 3. 5 66. 8 0. 58 243 2. 8 61 400 2.0 38. 2 0. 51 248 2. 7 65 400 3. 5 66. 8 0. 52 246 2. 8 61 400 7. 0 133.7 0. 55 238 2. 7 58 1, 000 3. 5 66.8 0. 53 250 2.8 63 1, 540 2. 0 38. 20. 56 252 2. 6 57 1, 540 3. 5 66. 8 0.50 251 2. 6 68 l, 540 7. 0 133. 70. 48 248 2. 5 72 4, 000 3. 5 66. 8 0. 57 251 2. 9 67 6, 000 3. 5 66.80. 62 253 2. 4 66 Control 6 None None 0. 57 254 2. 8 55 l Polyethyleneglycol. I Intrinsic viscosity 0! the polyester. I Softening point of thepolyester. 4 Tenacity in grams per denier of the corresponding yarn. 1Elongation in percent of the corresponding yarn at break.

Polyethylene terephthalate.

The expression, intrinsic viscosity, denoted by the symbol [1;] is usedherein as a measure of the degree of polymerization of the polyestersand may be defined as 1,1 limit? as C approaches 0 trichlorophenol and10 parts by weight of phenol) divided by the viscosity of the solventmixture per se measured in the same units and the same temperature, andC is the concentration in grams of polyester per hundred cubiccentimeters of solution.

These copolyesters were spun by the conventional melt spinning method byheating a quantity of the highly polymeric copolyester to a temperatureof about 280 C. and extruding through a 23-hole spinneret. The yarn waswound up at 600 yards per minute and drawn over a hot pin at 80 C. at adraw ratio to give a yarn elongation at the break of between 50 and 70%.A 23-filament yarn of approximately 70 denier was obtained. The yarnswere knit on a circular knitting machine into tubing which was thenboiled 01f according to the customary technique and tested for dyeaflinity. The results are given in Table H.

Table II w 1.. P2? Average Molecular Weight; of Polyethylene e g or Ce 9Glycol Used in Polymerization 2 531? 2531;; t

Polymer 2. 5 2. 0 2 3. 1 3 3. 6 5 4. 6 3 4. 2 3 3. 5 3 2. 6 None 1. 0

1 Based on light shades. Dark shades are not commercially possible onstraight polyethylene terephthalete by this standard dyeing technique.Dark shades on the copolymers of this invention are very favorable.

1 Polyethylene teraphthalate.

In determining the level of dye afiinity, dyeings were made with bothacetate dyes and vat dyes. With acetate dyes, the dye aflinity wasdetermined by dyeing to a predetermined light shade by using the minimumconcentration of dye in the dye bath to produce the given shade for adyeing cycle of a given time. These dye bath concentrations varied from1 to 5%. The dye afiinities shown in Table II are obtained bymultiplying the reciprocal of the dye bath concentration by 5 so as torelate all the numbers to a value of 1 for the control. The dyeings wereperformed by employing the given concentration of dye in an aqueous bathcontaining 50 grams of water for each gram of fabric to be dyed and 3%of a dispersing agent such as Alkanol DW (the sodium salt of an alkylaryl sulfonate). The dyeings were carried out at 212 F. for 60 minutes.Typical examples of the acetate dyes employed are the dyes having thefollowing color indices: PR-228 (blue), PR-61 (red), PR-238 (red), andPR-43 (orange). The polyethylene glycols which are generally used arethose having molecular weights of about 400 to about 4,000 or, in theformula above 11 may vary from about 6 to about 89.

With vat dyes it was found that a similar sort of rela' tionship heldwith respect to dye affinity as is given for the acetate dyes in TableII. In dyeing with the vat dyes, they were first reduced to the solubleleuco form by the alkaline reduction commonly employed in the art. Hereagain the dye aflinity was determined by dyeing to a predetermined lightshade by using the minimum concentration of dye in the dye bath to givethis shade for the given dyeing cycle. These dye bath concentrationsvaried from 1 to 5%. The dye bath contained 50 grams of water for eachgram of fabric but before adding the fabric the pH of the dye bath wasbrought to within the range of 5 to 7 by adding approximately 4.5 gramsper liter of glacial acetic acid and to maintain the dye in the reducedstate there was also added 10 grams per liter of Sulfoxite C (sodiumformaldehyde sulfoxylate). The dyeings were carried out at the boil fora total of 60 minutes. Among the vat dyes employed were those having thefollowing color indices: 1101 (green), 1105 (violet) and 196 (orange).The dyeing aflinity of the copolyesters of this invention for the vatdyes was from 2 to 5 times better than the dyeing afiinity ofpolyethylene terephthalate.

The polymeric esters of this invention are derived from terephthalicacid, ethylene glycol and polyethylene glycols of the above formula.Although these copolyesters may be produced by direct esterification ofterephthalic acid with ethylene glycol and the described polyethyleneglycols, it is generally preferred to carry out the reaction throughester interchange employing an ester of terephthalic acid (e. g.dimethyl terephthalate) or other of its ester forming derivatives. Thecopolyesters have melting or softening points above 200 C. and arereadily formed into films and filaments. Orientation is accomplishedreadily by cold drawing, and filaments of great strength and pliabilityare produced upon drawing. In general, the polymers of this inventionhave the properties disclosed for the polymers of U. S. 2,465,319, and,in addition, they have superior dye afiinity, a most importantcommercial advantage.

Any departure from the above description which conforms to the presentinvention is intended to be included within the scope of the claims.

I claim:

1. A dyeable polymeric ester derived from terephthalic acid, ethyleneglycol and a polyethylene glycol having a formula wherein n representsan integer within the range of l to 135, said polymeric ester having asoftening point of at least 200 C., the said polyethylene glycol beingpresent in amount not more than 10% by weight based on the terephthaliccomponent.

2. A dyeable polymeric ester derived from terephthalic acid, ethyleneglycol and a polyethylene glycol having the formula wherein n representsan integer within the range 6 to 89, said polymeric ester having asoftening point of at least 200 C., the said polyethylene glycol beingpresent in amount not more than 10% byweight based on the terephthaliccomponent.

3. A dyeable polymeric ester having a softening point of at least 200 C.capable of being shaped into article's such as films and filaments, saidester being derived from bis-,B-hydroxyethyl terephthalate and apolyethylene glycol having the formula wherein n represents an integerwithin the range of 1 to 135, the said polyethylene glycol being presentin amount not more than 10% by weight based on the terephthaliccomponent.

4. A dyeable polymeric ester having a softening point of at least 200 C.capable of being shaped into articles such as films and filaments, saidester being derived from reacting a polyethylene glycol with thereaction product of ethylene glycol and dimethyl terephthalate, the saidpolyethylene glycol being used in the reaction in amounts of about 1% toabout 10% based on the weight of said dimethylterephthalate, and thesaid polyethylene glycol having the formula References Cited in the fileof this patent UNITED STATES PATENTS 2,534,028 Izard Dec. 12, 19502,562,878 Blair Aug. 7, 1951 2,578,660 Auspos et al. Dec. 18, 1951

1. A DYEABLE POLYMERIC ESTER DERIVED FROM TEREPHTHALIC ACID, ETHYLENEGLYCOL AND A POLYETHYLENE GLYCOL HAVING A FORMULA